I know that the color codes tell you whether its neutral and other purposes, but do i need to find the same colored wire to extend one, or do i need the same one? And are they just for safety purposes?
Wherever you are, follow the local color code scheme. Not for you, but to protect the next poor slob who has to work in that box.
In the UK, it is a common misunderstanding that red is always live, and black or blue is neutral. While it is rare for a red wire to be used as a neutral, it is possible. And because twin and earth cables are so cheap, they are often used between ceiling roses and switches, so that the black or blue is live when the switch is in the ON position. It is good practice to mark this wire with a red sleeve to warn that it is NOT a neutral, but this doesn't always happen. It isn't a legal requirement for an extension to be the same colour but the wire should be the same current rating. In the UK, the modern system was designed to avoid cable joins in inaccessible places, like connection boxes between floor and ceiling, where a bad connection was more likely to start a fire.
In the US the colors generally have to stay the same. There are exceptions, the code book is a big book. Switches have some exceptions, like a white could have been used in existing installation as a hot from a light to a switch, a white could be marked and used as a hot on a 240v circuit, and the colors from one side of a switch may change colors, and if you have fed a multiwire circuit with 12/3 or 14/3 NM cable you can extend the red and white circuit with a black and white, but generally unless you can find an specific exception that matches your installation then for an extension the color needs to match.
Colors are not universal. Generally, red and green are power wires, black and white are ground.but not always. Its mostly for safety or for ease of connecting wires. For example, instructions for wiring in something would be confusing as hell if there was no way to tell what wire does what. Most items will come with an manual that say what each colored wire is, and what it does, so you know how to wire everything up correctly. You do not need to use the same color, as long as you can keep everything straight so you do not hook things up wrong. However, you should use the same size of wire.
